[Boatanchors] soldering/desoldering on boatanchors
WA5CAB at cs.com
WA5CAB at cs.com
Thu Feb 16 10:57:06 EST 2006
Gene,
What I had tried to say the other day was that tip temperature and wattage
are independent variables when the iron is being designed. Rated temp
temperature of an iron will be at some standard temperature and pressure and probably
something like 30-40% relative humidity. And touching nothing else (but air).
When you "load" the tip to solder or de-solder something, the tip temperature
will drop, how much depending on wattage, tip size and thermal load (thermal
resistance). If the iron is temperature controlled, more watts will be fed
into the heating element to try to hold the temperature up. But eventually it
will run out of oomph.
Also, rated tip temperature and wattage are not directly related. For 60/40
tin-lead solder, you need a tip temperature (working) in the 850 F range.
Regardless of the wattage.
For soldering something like a twist-lock capacitor that's soldered to a
chassis, or the top caps on rectangular can military capacitors (like the triple
.05's in BC-312/342's for example), you need a tip, to begin with, with more
surface area. Not just higher wattage. The tips on guns don't vary that much
in size. Regardless of the wattage. Even if you double the size over the
typical, you still don't have much surface area to work with. For doing what
you're trying to do, I'd recommend an iron of 120 or 150 watts, rated at 850, not
1000/1050 F, and with a diamond or pyramid tip of 5/8" or 3/4" diameter.
On the subject of soldering guns, I'll only say that I've got a Weller
somewhere, just in case I ever come across anything it's good for. If you must have
a pistol grip unit, I recommend the Wahl pistol grip rapid-heat iron. Among
other places, they're available from McMaster and Sears.
In a message dated 2/16/2006 9:10:51 AM Central Standard Time,
ehertz at tcaf.org writes:
> Well, if anyone is interested, the radio shack model 64-2185 does not do a
> good job for melting big solder joints. I am working on desoldering a can
> type capacitor from a PCB (oops, did I say pcb? I meant chassis ;-) ) and it
> just can get the solder melted enough to do a good clean up job. This is despite
> an 840F high temp.
>
> However, the unit does seem very nice for regular work, so I'll keep it.
>
> For desoldering bigger jobs, I am now considering getting radio shack model
> 64-2187 150W/230W gun type. Any opinions on this amount of wattage? I know
> that I have to be careful to not destroy everything in its path at this
> wattage.
>
> By the way, I know the real way to go is a hakko/weller/Xytronic, but if I
> told my wife I just paid $300 for a soldering iron, she would promptly solder
> together parts of my genitalia.
>
> Usual disclaimers, I do not own radio shack or even work there.
>
Robert & Susan Downs - Houston
<http://www.wa5cab.com> (Web Store)
MVPA 9480
<wa5cab at cs.com> (Primary email)
<wa5cab at houston.rr.com> (Backup email)
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